This question already has an answer here:
The government is a totalitarian oligarchy, and is relatively new. There is no organized opposition yet. The government is pretty well organized. It is extremely popular among the 80% of the population (cult of personality level popular), and 20% of the population dislike it but are terrified and docile at the moment.
They have modern technology, so manufacturing is somewhat automated and farming is heavily automated. They have access to modern high yield crop cultivars, GMOs, fertilizers, and modern pesticides. Their medicine is modern. Infrastructure is well developed, the population is educated and vaccinated. The population is used to deprivation and hardship, and can survive on the bare essentials without unrest. They do not require entertainment, eat extremely bland food, work long hours for seven days a week without complaint, and live mainly in shacks and tiny apartments in prefabricated concrete high rises, so that almost all resources can be devoted to capital and military goods.
They are in a state of total war against an existential threat, so people are clinging to the government desperately, even the ones that hate it, as they do not want to die. How large of a military (including combat forces and logistics people) can be mobilized for at least 5 years, without causing mass starvation? Even the dissidents can be mobilized, as they will find it difficult to make trouble if led by loyal NCOs and officers and controlled by secret policemen.